(i) Field of the Invention
The invention is in respect of a station for running foam-plastics material into shut molds, having a mixing head, a first driving system for moving the mixing head to the inlet opening of the mold in question into which plastics material is to be placed, and a second driving system for moving the mixing head into, and out of, the inlet opening. In the present invention the wording "foam-plastics" or "foam-plastics material" is used to have the sense of material designed for making foamed workpieces.
(ii) The Prior Art
In the case of prior filling station design the molds have to be stopped for movement of the mixing head to the inlet opening and for inlet of the plastics material into the inside of the mold. In the case of a production line having a number of mold carriages hanging from an endless transporter chain, such a stop-go operation of the system makes necessary the use of a driving motor with a high power, and a high level of power use making for heavy wear of the plant, because all mold carriages have to be stopped at certain times and then speeded up again. So far, however, this shortcoming has not been generally of much weight, because the use of shut molds has only been necessary in special cases; in fact, currently, most workpieces made of foam-plastics material on a mass scale are produced by the steps of: firstly causing distribution of the plastics material in the mold while still open, something which is readily possible even if the molds are moved without stopping, and then, only later, shutting the mold for foaming of the material. Presently, however, use is being made to an ever increasing degree of quick-foaming plastics materials for manufacture on a mass scale as well, such plastics materials expanding upwards to the parting line of the mold before the mold may be shut. In such cases, loss of material from the mold is likely, this being a shortcoming not only with respect to the quality of the work, but furthermore in respect to keeping the plant clean and in running order. So, in view of the currently marketed foam-plastics materials, which have to be processed at high speed, it is necessary for the mold to be shut when the plastics is run into it in many cases in which, earlier, the process was undertaken with the mold open.